Published paper review, numero uno…Leigh Syndrome- A mitochondrial DNA related disease.

So I must express how much I disliked doing this published paper review. My reason being is that many publish papers that I could sourced online were not free and also those that I did manage to have access to were very long and complex to interpret and comprehend. I decided to base my review on an organelle associated disease when I came across an article on Leigh syndrome. Before my conducting my research I had actually never heard of Leigh syndrome. I must say however, I am genuinely depressed after reading about how young children are affected by this disorder.I hope that my review on Leigh syndrome enlightens my readers and inspires you to do more research and truly hope that maybe one of the biochemians reading this blog becomes the scientific savior to discover the cure for such a terrible disease.

Leigh Syndrome is also known as juvenile subacute necrotizing encephalopathy and is associated with  Mitochondrial DNA mutation. It is a severe neurological disease that usually arises between 3 to 12 months of age and often occurs after viral infection.  This disease is associated with psychomotor regression as well as gradual loss of mental ability. Close to half of all affected individuals perish before age three due to respiratory or cardiac failure. Very few individuals develop this disorder in their adulthood.

Characteristic symptoms of Leigh’s disease include dysphagia (difficulty swallowing) and  persistent vomiting. Hyperventillation or irregular respiration , hypothermia and hyperthermia may be caused by brain lesions. The muscles of individuals suffering with Leigh syndrome are usually negatively affected. The individual may develop hypotonia or weak muscle tone, dystonia or involuntary muscle contractions as well as axtaxia or movement and balance problems. Peripheral neuropathy characterized by weakness or loss of sensitivity in limbs is common with affected individuals hence their ability to move is impaired.The eyes of the affected individual can also be affected and they may experience eye movement disorders and retinitis pigmentosa.

Cardiac ailments such as hypertrophic cardiomyopathy, hepatic disorders and renal disorders such diffuse glomerulocystic kidney damage are also common amongst affected individuals. The majority of affected individuals will show progressive deterioration with interfused with stages where they may show improvement which can last up to ten years in some cases. However it is more likely that the person will die around age 2 to three years. Also associated with Leigh syndrome are high levels of lactate in urine, blood or  cerebrospinal fluid of patients.

Brain lesions  (detected via Magnetic resonance imaging) are found in the  basal ganglia (movement associated region) the cerebellum (region associated with balance,coordination and movement) as well as the the brainstem. Demyelination  (loss of myelin coating around nerves) in conjuction with these brain lesions reduces the ability of muscle activation as well as the relay of sensory impulses back to the brain.

About 30% of Leigh syndrome is mitochondria DNA related. Most of the genes associated with Leigh syndrome are involved in energy generation in the mitochondria. This disease can be inherited by X linked transmission, autosomal linked transmission, maternal transmission or it may be sporadic. Many of the gene mutations associated with this disease affect proteins of protein complexes that are involved in oxidative phosphorylation (the process whereby the mitochondria uses oxygen to break down food into energy for use by the cell). There are other nuclear DNA mutations characteristic of Leigh’s syndrome which also affect steps concerning energy production and oxidative phosphorylation. Researchers link impaired oxidative phosphorylation to cell death  and tissues that require large amounts of energy including the brain, heart and muscles are especially affected.

There is unfortunately no cure for Leigh’s syndrome and the treatment is limited and not entirely effective.



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